nsresourced: downgrade benign log message to debug

This is very noisy as there's a dozen of these message every
time it gets called, and it's not really an error but an
expected situation, so downgrade from info to debug

src/nsresourced/userns-restrict.c

@@ -151,7 +151,7 @@ int userns_restrict_install(
                                 link = NULL;
                         } else {
                                 linked = true;
-                                log_info("userns-restrict BPF-LSM program %s already attached.", ps->name);
+                                log_debug("userns-restrict BPF-LSM program %s already attached.", ps->name);
                         }
                 }